(1) Field of the Invention
This invention relates to wet-processing of cotton textiles. More specifically, this invention relates to the processing of cotton textiles with vinylic monomers.
(2) Description of the Prior Art
Most processes for treating durable-press cotton textiles with polymeric finishes consist of padding solutions of polymers onto said textiles and then curing or drying the product at high temperatures in gas-fired ovens. This decreases the rate at which polymers are washed out of said textiles in normal usage. However, at the finishing plant, thermal pollution of both the air and wash-water effluents, chemical pollution of the atmosphere by thermal decomposition of the polymers during curing, heating, and drying, at high temperatures, of the treated textile products, chemical pollution of wash-water effluents that contain degraded polymeric fragments and solvents used in the solutions of polymers thereby leading to increased biochemical oxygen demand requirements of streams and rivers, and environmentally degrading effects occur. Further, a non-controllable, non-definitive, non-covalently linked reaction, in the sense of composite formation, occurs between the polymers and fibers of the said textiles.
There are increasing emphases on developing more sophisticated finishing processes for durable-press cotton textiles, so that known and controllable chemical reactions occur between finishing agents and cotton textiles. Development of these types of processes for cotton textiles will make said textiles more competitive in properties with man-made textiles where chemistry is known and controlled. In summary, the present state of the prior art in finishing durable-press cotton textiles, particularly in attempts to impart polymeric surface properties to said textiles, is in the realm of "art of finishing textiles" with little or no "science of finishing textiles."
Also, with increasing emphases on environmental protection and alternate sources and uses of energy, the prior art of textile finishing is based on thermal curing usually in high temperature ovens heated by natural gas which has predictably both short-term and long-term increases in cost and long-term decreases in supply. Further, the prior art leads to thermal pollution of the environment, both air and water. The prior art of textile finishing also uses catalytic agents that must subsequently be washed out of the textile product, leading to water and stream pollution and high usage of purified water, a critical and energy consuming resource in many regions. Thermal curing of textile finishing agents by the prior art leads to thermally initiated degradation of the finishing agents and to both air and water pollution. Further, unreacted textile finishing agents and degraded fragments of said agents must be washed out of the textile product leading to high water usage and pollution of streams. These environmental insults by textile finishing processes of the prior art are becoming less and less acceptable.
The state of this art is summarized by H. B. Goldstein in the article "Durable-Press Treatments" by G. L. Drake, Jr., and W. A. Reeves in the article "Flame-Resistant Textiles," in the book "Cellulose and Cellulose Derivatives," High Polymers, Vol. V, Part V, edited by N. M. Bilales and L. Segal, Wiley-Interscience, New York, 1971, pp. 1095-1113 and pp. 1293-1331, respectively.
Development of more sophisticated finishing processes for durable-press cotton textiles based on free-radical initiated chain reactions of chemical reagents with cellulose molecules comprising the textile fabrics could lead to a more scientifically controlled finishing of textiles and improvement of their useful textile properties. The use of "free-radical curable" finishing agents on cotton, if the reactions were initiated by exposure of the fabrics and chemical reagents to high-energy radiation and ultra-violet light radiation, both non-polluting catalysts, could lead to a more efficient reaction of reagent with cotton, for example, 95 percent reaction for radiation processes as compared with about 70 percent reaction for thermally-initiated processes, with a minimum of environmental pollution in subsequent washing in the case for radiation processes. "Free-radical curable" chemical reagents must contain vinyl groups, so that chain reactions can be initiated. High-energy radiation interactions with cellulose comprising the fabric and the added chemical reagent are non-chemically specific and could lead to the formation of initiating free radicals on the cellulose molecules or the chemical agent. Processes for using high-energy radiation to initiate free-radical reactions of vinyl monomers have been summarized in an article entitled "Graft Polymerizations onto Polysaccharides" by Jett C. Arthur, Jr., published in Advances in Macromolecular Chemistry, Volume 2, pages 1 through 87, 1970.
The long-term interests in the effects of ultraviolet light radiation on cotton have been in improving the weather resistances of cotton products. Glyn O. Phillips and Jett C. Arthur, Jr., have reviewed the technical literature in this area in two review articles entitled "Chemical Effects of Light on Cotton Cellulose and Related Compounds. Part I. Primary Processes in Model Systems and Part II. Photodegradation of Cotton Cellulose" in the June and July 1969 issues of the Textile Research Journal, Volume 44, pages 497-505 and pages 572-580, respectively. It was subsequently determined that oxidative depolymerization reactions of cellulose were the predominant chemical reactions initiated on exposure of cotton to ultraviolet light radiation and that macrocellulosic free radicals were formed. The applicants' research group determined then to develop cotton textile finishing processes based on use of ultraviolet light radiation to initiate free-radical chain reactions with chemical finishing agents that contain vinyl groups, the presence of these groups being essential to maintain chain reactions. Jett C. Arthur, Jr., and Oscar Hinojosa reported on "Photopolymerization and Depolymerization in Glassy States and Fibrous Cotton Cellulose" in the Journal of Applied Polymer Symposia, No. 26, pages 147-156 (1975). Alden H. Reine, Jett C. Arthur, Jr., and Norman A. Portnoy were issued U.S. Pat. No. 3,926,555 on "Modification of Cotton Textiles and Cotton/Polyester Textile Blends by Photoinitiated Polymerization of Vinylic Monomers" which disclosed that graft polymerization of diacetone acrylamide, acrylamide, N,N-methylenebisacrylamide, N-vinyl pyrrolidone, acrylic acid, and methacrylamide on cotton/polyester textile blends improved the moisture regain and personal comfort properties of the cotton/polyester textile blends.